<?php
/**
 * @link http://www.tintsoft.com/
 * @copyright Copyright (c) 2013 TintSoft LLC
 * @license http://www.tintsoft.com/license/
 */
namespace Leaps\Helper;

use Leaps\Base\InvalidParamException;
use Leaps\Base\Arrayable;
use Leaps\Web\JsExpression;

/**
 * BaseJson 提供 [[Json]]具体的实现
 *
 * 不要直接使用 BaseJson. 请使用 [[Json]].
 *
 * @author Tongle Xu <xutongle@gmail.com>
 * @since 5.0
 */
class BaseJson
{
    /**
     * 将给定值编码成一个JSON字符串。
     * The method enhances `json_encode()` by supporting JavaScript expressions.
     * In particular, the method will not encode a JavaScript expression that is
     * represented in terms of a [[JsExpression]] object.
     * @param mixed $value the data to be encoded
     * @param integer $options the encoding options. For more details please refer to
     * [[http://www.php.net/manual/en/function.json-encode.php]]
     * @return string the encoding result
     */
    public static function encode($value, $options = 0)
    {
        $expressions = [];
        $value = static::processData($value, $expressions, uniqid());
        $json = json_encode($value, $options);
        return empty($expressions) ? $json : strtr($json, $expressions);
    }

    /**
     * 解码给定的JSON字符串到PHP数据结构。
     * @param string $json the JSON string to be decoded
     * @param boolean $asArray whether to return objects in terms of associative arrays.
     * @return mixed the PHP data
     * @throws InvalidParamException if there is any decoding error
     */
    public static function decode($json, $asArray = true)
    {
        if (is_array($json)) {
            throw new InvalidParamException('Invalid JSON data.');
        }
        $decode = json_decode((string)$json, $asArray);
        switch (json_last_error()) {
            case JSON_ERROR_NONE:
                break;
            case JSON_ERROR_DEPTH:
                throw new InvalidParamException('The maximum stack depth has been exceeded.');
            case JSON_ERROR_CTRL_CHAR:
                throw new InvalidParamException('Control character error, possibly incorrectly encoded.');
            case JSON_ERROR_SYNTAX:
                throw new InvalidParamException('Syntax error.');
            case JSON_ERROR_STATE_MISMATCH:
                throw new InvalidParamException('Invalid or malformed JSON.');
            case JSON_ERROR_UTF8:
                throw new InvalidParamException('Malformed UTF-8 characters, possibly incorrectly encoded.');
            default:
                throw new InvalidParamException('Unknown JSON decoding error.');
        }

        return $decode;
    }

    /**
     * 前置预处理数据发送给“json_encode()”。
     * @param mixed $data the data to be processed
     * @param array $expressions collection of JavaScript expressions
     * @param string $expPrefix a prefix internally used to handle JS expressions
     * @return mixed the processed data
     */
    protected static function processData($data, &$expressions, $expPrefix)
    {
        if (is_object($data)) {
            if ($data instanceof JsExpression) {
                $token = "!{[$expPrefix=" . count($expressions) . ']}!';
                $expressions['"' . $token . '"'] = $data->expression;
                return $token;
            }
            $data = $data instanceof Arrayable ? $data->toArray() : get_object_vars($data);
            if ($data === [] && !$data instanceof Arrayable) {
                return new \stdClass();
            }
        }

        if (is_array($data)) {
            foreach ($data as $key => $value) {
                if (is_array($value) || is_object($value)) {
                    $data[$key] = static::processData($value, $expressions, $expPrefix);
                }
            }
        }

        return $data;
    }
}
